2007 Articles

A role for tropical tropospheric temperature adjustment to El Niño–Southern Oscillation in the seasonality of monsoonal Indonesia precipitation predictability

Giannini, Alessandra; Robertson, Andrew W.; Qian, Jianhua

We describe the seasonality in the variability and predictability of Indonesian monsoonal climate, dominated by the El Niño–Southern Oscillation (ENSO) phenomenon, and interpret it in light of theories of the development of the global ENSO teleconnection which explain the evolution of the response of the tropical ocean atmosphere to ENSO’s perturbation. High predictability during the dry and transition seasons, which coincide with ENSO growth, is expected from the coherent large-scale response to ENSO’s initial perturbation. As the tropical ocean-atmosphere equilibrates to ENSO, and ENSO itself begins to decay, its direct influence diminishes, and regional features associated with the delayed response to ENSO become more prominent. Consistent with this interpretation, in a preliminary observational analysis of station data over Jawa we find that predictability is high during the growth phase of ENSO. We also find that at these regional scales there may be more predictability than previously thought as ENSO decays. Finally, we show that a simple one-tier prediction system, i.e., a system where the evolution of oceanic and atmospheric anomalies is internally consistent, better captures the intrinsic coupled nature of the ENSO teleconnection, compared to a two-tier system where the ocean forces the atmosphere, but does not respond to its feedback.